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8.0

Delphi Threads with TBItmap, TJpegImage, TGraphics32

Asked by Xor2 in Graphics and Delphi Programming, Delphi IDE

Tags: Delphi, Thread, TBitmap, Graphics32, TBitmap32

Hello,

   I have a procedure which performs some operation on jpg files (like transformations, etc).

I am;

  - reading pixel from canvas
       ACanvas.Pixels[X,Y];
  - drawing on canvas
       Bitmap.Canvas.Draw(0,0,jpg);
  - assign bitmap from another source
       Bitmap.Assign(LBitmapPomn);

The problem is that when i Run this procedure in a one thread everything is perfectly allright. I don't have memory leaks nor I have increased number of GDI objects and
the memory in the process manager varies from 50 to 100 mb and after this it returns to its default value.

The problem starts when i want to run this procedure in 4 threads. I have memory leaks. Memory inscreased to 1.7 gb, gdi +500 objects and so on..

I know only that Graphics32 component is thread-safe.
What about TBitmap, TJpegImage?
Which operation with this classes I should "Lock", should I lock?

Could the memory leak occur because of using these components in more than 1 thread?

How Can i fix my code?
Can I,  for instance use Graphics32 canvas without locking it.
Can I perform all this task only with Graphics32, which would gurantee thred safeness?

Thanks for help in advance..
 
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[+][-]12/22/08 07:47 AM, ID: 23227119Accepted Solution

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Zones: Graphics and Delphi Programming, Delphi IDE
Tags: Delphi, Thread, TBitmap, Graphics32, TBitmap32
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Solution Provided By: ciuly
Participating Experts: 2
Solution Grade: A
 
[+][-]12/22/08 07:52 AM, ID: 23227148Assisted Solution

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